19,437 research outputs found
METAMORPHOSE VI – the Virtual Institute for Artificial Electromagnetic Materials and Metamaterials: Origin, mission, and activities
In this paper, we outline the background, mission, and activities of the Virtual Institute for Artificial Electromagnetic Materials and Metamaterials (METAMORPHOSE VI). This international association, founded in the framework of the FP-6 Network of Excellence METAMORPHOSE, aims at promoting and developing research, training, and dissemination activities in the emerging and highly dynamic field of advanced electromagnetic materials and metamaterials at both European and International levels. More than 300 researchers are currently associated with the METAMORPHOSE VI which networks them together in a learnt society. After a brief description of the association and its mission, we present an overview of the activities developed by the METAMORPHOSE VI, with a particular emphasis on the coordination of the European Doctoral Program on Metamaterials (EUPROMETA) and the organization of the International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – metamaterials congress
Sex determination in Bonellia viridis (Echiura : Bonelliidae) : population dynamics and evolution
In the echiuran worm Bonellia viridis Rolando, the vast majority of sexually
undifferentiated larvae metamorphose into dwarf males that live inside the female
when exposed to females, but differentiate into females when developing in the absence
of females. By means of a spatially explicit, individual-based model the authors examine how
this specific form of environmental sex determination (ESD) affects dynamics of
Bonellia populations and investigate the selective advantage of ESD over the more
widespread genotypic sex determination (GSD). Population dynamics of Bonellia
appear rather simple and not too sensitive to parameter changes around their measured
values, or to changes in distribution and sizes of inhabitable patches. Starting even from
low sizes, populations soon attain equilibrium densities. Explored aspects of population
dynamics indicate an advantage of ESD over GSD. Moreover, simulated invasibility
experiments show that while the maternal inheritance scenario allows for fixation of
GSD under some limited conditions, both the classical and proportional inheritance
scenarios always lead to fixation of ESD in the population. This article also shows that only the
ability of ESD larvae to adapt their ultimate sex both in competition for empty burrows
and for mating within females gives them a competitive edge over nonadaptive response
to feminising and/or masculinising signals and generally leads to fixation of ESD by
small step evolution. The original hypothesis of Charnov and Bull thus needs to be
refined in the sense that along with females forming an unpredictable resource for
males, empty burrows are an unpredictable resource for femalespeer-reviewe
WETLAND OCCUPANCY OF POND-BREEDING AMPHIBIANS IN YOSEMITE NATIONAL PARK, USA
We estimated wetland occupancy and population trends for three species of pond-breeding anurans in Yosemite National Park from 2007 – 2011. We used a double survey technique in which two observers independently surveyed each site on the same day. Double surveys allowed us to calculate detectability for the three most common anurans within the park: Rana sierrae, Anaxyrus canorus, and Pseudacris regilla. Annual estimates of detectability were generally high; mean detectability ranged from 73.7% + 0.6 (SE) for any life history stage of A. canorus to 86.7% + 0.7 for sites with P. regilla reproduction (eggs or larvae present). Detectability was most variable for Anaxyrus canorus, which ranged from 45.9% to 99.7%. The probability of occupancy for R. sierrae was highest in larger, low-elevation wetlands that lacked fish. Anaxyrus canorus were more common in shallow high-elevation ponds; their occurrence was minimally impacted by the presence of fish. Finally, occurrence of P. regilla was largely unrelated to wetland size and elevation, but like R. sierrae, they were less likely to occupy sites with fish. Occupancy showed no trend over the five years of our study for R. sierrae or A. canorus when considering either sites with any life stage or only sites with reproduction. However, P. regilla showed a modest downward trend for sites with any life stage and sites with reproduction. Our results for R. sierrae run counter to expectations given recent concern about the decline of this species, while our findings for P. regilla raise concerns for this widespread and generally common species
Rethinking the education of chemists - the odyssey is over, time for action!
Chemistry is a mature discipline with a distinguished pedigree and a long tradition, but times are changing and student numbers in chemistry are declining. The need for a reappraisal of what constitutes chemistry and a chemistry education at the beginning of the new millennium, is apparent. The paper examines some of the current issues surrounding chemistry and chemistry teaching and suggests ways in which we might go forward. A message of vision and imagination, applying a little of the ideals of Zarathustra in the setting of, '2001, A Chemistry Odyssey', is promulgated. [Chem. Educ. Res. Pract.: 2003, 4, 83-96]
The Role of Adult Fiddler Crab Environmental Acoustic Cues and Chemical Cues in Stimulating Molting of Field-Caught Megalopae
In mid-Atlantic estuaries, three fiddler crab species, Uca pugilator, Uca pugnax and Uca minax co-occur, with their adults occupying different habitat types distinguished by salinity and sediment size. Some evidence exists that selective settlement is responsible for this separation but the mechanism is largely unknown. We tested the hypothesis that field-caught megalopae would accelerate metamorphosis in the presence of adult species-specific environmental acoustic cues and conspecific chemical cues. We placed megalopae in seawater with and without adult chemical cues, exposed them to one of three sound treatments for 8 days, and recorded the time each megalopa took to metamorphose. In the absence of adult chemical cues, very few megalopae molted regardless of sound treatment. Molting in the presence of habitat sound and chemical cues varied by species. Many U. pugilator molted in all sound and odor combinations, including no odor/sound. U. pugnax was stimulated to molt by chemical cues from either U. pugilator or U. pugnax, but molting was similar across sound treatments. Our results do not support the hypothesis that sound stimulates molting by fiddler crab megalopae, but support the role of chemical odors from adults as molting cues
RESEARCH PERSPECTIVES:: STASIS SHMASIS - WHAT SALAMANDERS WERE REALLY DOING IN THE YULE LOG
Whether it is their nocturnal habits, their ability to regenerateentire limbs and tails with functional neurons,or simply their ability to emerge unsinged from a burningyule log, salamanders have long intrigued humansand witches alike. Salamanders are marvelous beasts inmany other ways
LIFE HISTORY SWITCH POINT PLASTICY IN RESPONSE TO POND DRYING ALYERS METAMORPH ALLOMETRY AND JUMPING PERFORMANCE
Animals with complex life cycles can cope with environmental uncertainty by altering life history switch points through developmental plasticity. Pond drying is an important factor which may alter life history switch points in aquatic organisms. Many amphibians can plastically respond to changes in pond drying by emerging earlier, but few studies have examined the post-metamorphic consequences for performance. To investigate the potential carry-over effects of plasticity to pond drying, we studied the túngara frog, Physalaemus pustulosus, a tropical anuran that breeds in highly ephemeral habitats. We conducted a field study with three different water depth treatments in 60 L mesocosms and measured time and size at metamorphosis, hind limb length and jumping performance. We also conducted a complimentary laboratory study that manipulated resources and water depth. In the field experiment, metamorphs from dry-down treatments emerged earlier, but at a similar size to constant volume treatments. In the laboratory experiment, metamorphs from the low depth and dry-down treatments emerged both earlier and smaller. In both studies, frogs from dry-down treatments had relatively shorter hind limbs, which negatively impacted their jumping performance. Reductions in resources delayed and reduced size at metamorphosis, but had no effect on jumping performance. We demonstrate that conditions experienced early in ontogeny can transcend the metamorphic boundary by erasing the relationship between hind limb length and jumping performance
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